Since 1980, automatic egg injection machines have been useful to the hatchery industry in the inoculation of turkey eggs against mycoplasma melangridis (MM). The method and apparatus have evolved, as exemplified by two related patents; U.S. Pat. No. 4,040,388, Miller and Raymond Sheeks, issued Aug. 9, 1977, and U.S. Pat. No. 4,593,646, Miller and Perry Sheeks, Jun. 10, 1986. Another related patent, U.S. Pat. No. 4,469,047, Miller and Perry Sheeks, issued Sep. 4, 1984, discloses an invention for the injection of formulations through the large or top end of the egg, whereas the two former patents emphasize injection through the small end.
Field experience with the above-cited apparati have shown that injections of gentamicin and streptomycin formulations, trade-named as Garasol and Tylusin, do suppress M and other avian diseases, but with an accompanying one to two percent depression of the hatch. Frequently, unexplained depressions of five to seven percent occur.
More recently, field trials directed by Dr. E. J. Roble of the U.S. Department of Agriculture, Avian Physiology Laboratory, Beltsville, Md., revealed that the depressions sometimes up to eleven percent, were most probably caused by direct contamination by the machine or formulations and by cross contamination between eggs caused by the needles. The degree or hatch depression is directly related to the lack of sanitation of the egg shell, injection solution, and machine plumbing and also to the percentage of bad eggs in the lot. Results of those field trials are summarized in a letter from Roble to one of the present inventors dated May 18, 1988. A copy of that letter is attached and referred to as Reference #2.
Clearly, a means of controlling contamination in the egg injection process is necessary. One approach would be to incorporate exhaustive sanitization procedures throughout the hatchery and to cull out bad eggs from entering the process. However, this approach is not practical in the normal hatchery as it would be prohibitively expensive. Prior use of heat to sterilize the needle and egg penetration area proved to be a constant problem in plugging the needles with cooked albumin. Cleaning of the needles in a bath after each injection, as is done by some machines presently utilized, will not sterilize either the egg shell, injection solution or machine plumbing. Ultraviolet light has beneficial germicidal effects, but requires more time to kill bacteria than the injection process will allow.
Prior attempts to test the viability of injecting various vitamins, nutrients and trace minerals to enhance the embryo have not been successful because the results have been masked by the depression of hatch rates due to contamination.
More recent attempts to vaccinate chicken embryos against Marek's disease (MD) by injecting the live virus vaccines, turkey herpesvirus (HVT) and SB-1 strain, have shown promise for immunizing the hatched avian species, as disclosed in U.S. Pat. No. 4,458,630 issued Jul. 10, 1984 to J. M. Sharma, et al. However, the process described in Sharma does not address the impact of contamination in the normal commercial hatchery environment, and in actuality may promote introduction of harmful bacterial infestation through the use or the carrier, chicken embryo fibroblast (CEF) tissue culture. Periodic severe hatch depressions may be expected as with the other avian embryo injection methods previously discussed. The problem of controlling bacteria without killing the beneficial live-virus vaccine remains with the referenced prior art.
The present invention overcomes the problems in the prior art and advances the art with regard to improvements to hatchability and disease control in the egg injection process, as will be revealed in the following disclosure.